"The truth is that this is the first post of the Valve Linux blog. This blog is where you can find the latest information from Valve about our Linux development efforts. Avoid the rumors and speculations that multiply on the Web. Instead, come to the source - a blog where people who are interested in Linux and open source game development can get the latest information on Valve's efforts in this arena. In this initial post, we'll introduce the team (and a bit of its history) and then give you a snapshot of what we're currently doing." Steam, Source, and Left 4 Dead 2 coming to Linux. We know why.

The games would be ported directly to Linux OpenGL while letting Windows pass through GPU access to LinuxVM, so (given proper CPU support) no additional SW layers.
Such a virtual console could ignite a sort of games ecosystem before they come out with the real HW on the market.